1. Field of the Invention
The present invention relates to a transmission system for transmitting information signals at various rates, the system comprising at least:
a data input port for receiving the transmit data at a certain data rate during a communication period, PA1 a transmit section for transmitting at a channel rate information signals present on at least one of its incoming channel ports over at least one transmit channel, a receive section for receiving the information signals coming from at least one of said channels so as to present them at at least one of its outgoing channel ports, PA1 an output data port for producing the transmitted data. PA1 a transmit distribution circuit for connecting said data input port to a certain number of incoming channel ports as a function of the data rate during said communication period, PA1 a receive restoring circuit for connecting in corresponding fashion a number of outgoing channel ports to the output port.
The present invention likewise relates to a transmitter station and a receiver station suitable for such a system.
2. Description of the Related Art
The invention finds important applications for offering to the users on board of motor cars a variety of telecommunication services: for example, telephone links which need a narrow passband and video links which need a very wide passband. This type of service is offered by the broadband ISDN system fulfilling the ATM protocol. This is described in the publication: "Asynchronous Transfer Mode" by J. P. Coudreuse et al., published in the journal Commutation et Transmission no. 3/1990. Thus there is the problem of allocating resources that remain limited especially in the field of radio telecommunications.
A system of this type is described in U.S. Pat. No. 4,870,641. In this system a group of preselected channels is allocated to ensure a high data rate, but is not of necessity assigned to a single communication. That causes this system not to be adapted to transmitting information signals in the radio mobile networks wherein the channels are frequency-division channels which utilize the radiowave propagation and for which it is necessary to connect terminals of different kinds. For reasons of radiowave propagation, the frequency-division channels relating to a link between a base station and a particular remote station are of necessity not suitable for a link to another remote station. Said Patent provides no teaching concerning dynamic transmit frequency allocation which takes the geographical position of stations into account, which stations form part of the system, nor any indication whatsoever as regards simultaneous transmission between several users.